Necrobacillosis in Deer

Murray Woodbury DVM, MSc.
Specialized Livestock Research and Development Program
Department of Large Animal Clinical Sciences
Western College of Veterinary Medicine
University of Saskatchewn
Saskatoon,
Saskatchewan S7N 5B4

Necrobacillosis is also known as
necrotic stomatitis, hepatic necrobacillosis,
foot rot, calf diphtheria and lumpy jaw. It produces a variety of
diseases,
with abscessation occurring in almost any body organ or joint cavity.
In
white-tailed deer it is usually seen as individual cases of lumpy jaw
or
as a fatal infection of multiple fawns.

Cause

Necrobacillosis is caused by Fusobacterium
necrophorum, an anaerobic,
gram negative, often highly filamentous rod-like bacteria. Being
"anaerobic"
means that it likes to grow in places where there is very little air or
oxygen. This organism is found in the intestines of many species as
part
of the normal flora. It survives well in wet soil that has a high
manure
content. Other bacteria are often associated with the disease, Arcanobacterium
pyogenes being the most common.

Geographic
distribution

F. necrophorum occurs
throughout the world. Outbreaks of necrobacillosis
in wild populations have been reported in mule deer in California, elk
in Wyoming, white-tailed deer and pronghorn antelope in Saskatchewan,
and
reindeer in Siberia (1,6,9). New Zealand and North American deer farms
suffer significant losses from the foot rot and necrotic stomatitis
(tongue
and throat abscesses) forms of the disease (7,10).

Transmission

Animals develop necrobacillosis
when a number of factors are present.
Stress such as heat, cold, overcrowding or poor nutrition predispose to
infection. Fusobacterium cannot penetrate intact skin. The organism
gains
entry into the body through cuts or abrasions to the skin or mucous
membranes.
In the mouth, grass awns, coarse feed, metal objects, and unevenly worn
or newly erupting teeth can penetrate or damage the oral lining and
create
points of entry. Contamination of the abrasions with soil containing F.
necrophorum results in an infection. Changes in the rumen
environment
such as grain overload or sudden changes in feed can damage the stomach
lining. This provides a portal of entry for Fusobacterium,
where
they may then pass to the liver, causing hepatic necrobacillosis, or to
other major organs.

In some situations the disease
appears to be contagious and there is,
no doubt, direct contamination of shared feed bunks and drinking water
by infected animals with open lesions. The infectivity or invasiveness
of F. necrophorum is enhanced by the presence of other bacteria
such as E. coli and A. pyogenes and the presence of
these
bacteria permit infection by relatively few F. necrophorum
organisms
(9).

Other
species affected

Cases of necrobacillosis have
been reported in many species of wild
and domestic hoofed animal. In farmed white-tailed and fallow deer,
necrobacillosis
is recognized as a serious problem of young or newly weaned fawns.
There
have been large die offs of wild mule deer and white-tailed deer,
reindeer
and elk (7). Heavy losses of kangaroos and wallabies have occurred in
zoos
and the wild (4). Foot rot can be a significant problem in cattle,
sheep
and bison and also wild hoofed stock (6).

Clinical
signs

The location in the body of
lesions determine what signs are seen. Affected
animals are usually depressed and have a fever. Often the hair coat is
rough and the animal is thin and doing poorly. Lesions involving the
mouth
are often deep, invading the surrounding soft tissue and bone creating
the classic swollen jaw or face. Animals may go off feed and begin to
lose
condition as the problem develops. In fawns the lack of nutritional
reserve
and toxic by-products of the infection lead to a more rapid death.

Lameness is seen when the
feet and
associated joints are involved. Swelling
between the toes is the first sign seen, followed by localized tissue
death,
spreading to the joints and bones in more advanced cases (5,7,10). In
the throat, necrotic laryngitis will show itself as loud wheezing.
Some dead tissue and bacteria may be sucked into the lungs causing
abscess
formation and pneumonia. Cases
of necrotic rumenitis or stomach abscesses frequently have few
signs except weight loss in chronic forms or apparent sudden death.

Post
mortem findings

The most common lesions are
necrotic ulcers or abscesses of varying
depth on oral, pharyngeal (throat), or laryngeal mucous membranes. In
severe
cases, lesions extend into the nasal cavity, upper and lower jaw bones,
larynx, trachea and lungs. Spread of F. necrophorum through the
bloodstream may cause abscesses in internal organs. The abscesses
contain
foul smelling, thick purulent material having a greenish tinge. Rumen
lesions
are characterized by well defined, yellow, raised foci of necrosis.
These
extend deep into the rumen wall and can perforate, leading to
peritonitis,
or infection of the abdominal cavity (10).

Diagnosis

Clinical signs and history are
usually sufficient to establish a diagnosis.
The organism is difficult to grow, making culture and isolation
difficult
without special culture swabs and growth medium. Identification of the
organism in lesions can be made with a flourescent antibody test (7).
There
is also a blood test (ELISA) for the detection of serum antibodies to F.
necrophorum in sheep and cattle (2). However, these tests may not
be
presently available to all pathology laboratories.

Treatment

Early detection of
necrobacillosis is important if the disease is to
be treated. The long term results of treatment are not encouraging.
Affected
animals should be isolated from healthy animals. Feeding and drinking
areas
and working facilities should be cleaned and disinfected to prevent
spread
of the organism. Antibiotics are indicated for therapy. Although, like
most drugs, they are not currently licensed for use in deer. Procaine
penicillin
is likely most effective with tetracyclines and sulfonamides being used
as well. Where possible abscesses should be drained and flushed to
remove
debris and toxins. Debris and pus from the lesion should not be allowed
to contaminate the treatment area. Collect and incinerate the material
in a plastic bag. Amputation of a toe may be required in severe cases
of
foot rot where there is bone and joint involvement.

Prevention

As with most diseases, prevention
is much more rewarding than treatment.
Good management practices form a large part of any control or
prevention
program.

Stress from overcrowding, social or hierarchy instability,
inappropriate
mixing of sexes and ages, or poor animal handling technique should be
minimized.

Good general hygiene should be practised with attention
paid to control
of excessive fecal contamination of paddocks, holding and handling
facilities,
and feeding equipment. Hay offered on the ground will become
contaminated
with urine and feces.

Do not use preventative antibiotics without a
diagnosis or good
evidence of infection. In the long term, if your problem is not
necrobacillosis, more problems will be created
than will be prevented.

Food structure (coarseness) is probably not as important
as the nutritional
quality of food. Poor quality food decreases resistance to disease in
general..
There is some evidence that mucosal skin integrity depends on adequate
vitamin A and C levels (4). Deficiency of these vitamins may predispose
animals to necrobacillosis infection by making invasion easier.

The type of soil underfoot may play a role in the
persistence and transmission
of F. necrophorum. Clay and other water retaining types of soil
are thought to support bacterial life better than well drained sandy
soils
(4). Whatever the soil type, avoid poorly drained paddocks and moist
areas
to raise deer.

Vaccination

Vaccination will never replace good management practices. However when
faced with persistent disease vaccination may be an option. There is no
commercial vaccine licensed for prevention of necrobacillosis in deer
but
variable results have been observed with Fusogard™ (Novartis).
Fusogard™ is a pure F. necrophorum bacterin designed
to prevent footrot and liver abscesses in cattle. Some deer producers
claim
to have achieved good protective results and others have been
disappointed.
Its usefulness in deer species has never been scientifically
established.

Because necrobacillosis is most
often a mixed bacterial infection (F.
necrophorum plus others), it may be that every farm outbreak
involves
a unique combination of bacteria, similar but different from each
other.
The use of "autogenous" vaccines may therefore hold more promise.
Autogenous
bacterins are made up separately for each infected farm from bacteria
derived
from infections on that particular premises. (Auto genous = self
generated)

Animals are inoculated with a
product made up from bacteria obtained
from lesions on that farm, creating a more specific and effective
immunity
to the necrobacillosis organisms. Autogenous vaccines have been used to
treat necrobacillosis in sick animals as well as prevent disease in
healthy
ones. Both uses have not been adequately tested in white-tailed deer
and
further investigation is needed to determine their usefulness.